Abstract/Summary

A common precursor to ice shelf disintegration, most notably that of Larsen B Ice Shelf, is
unusually intense or prolonged surface melt and the presence of surface standing water. However, there
has been little research into detailed patterns of melt on ice shelves or the nature of summer melt ponds.
We investigated surface melt on Larsen C Ice Shelf at high resolution using Envisat advanced synthetic
aperture radar (ASAR) data and explored melt ponds in a range of satellite images. The improved
spatial resolution of SAR over alternative approaches revealed anomalously long melt duration in
western inlets. Meteorological modelling explained this pattern by föhn winds which were common in
this region.Melt ponds are difficult to detect using optical imagery because cloud-free conditions are rare
in this region and ponds quickly freeze over, but can be monitored using SAR in all weather conditions.
Melt ponds up to tens of kilometres in length were common in Cabinet Inlet, where melt duration was
most prolonged. The pattern of melt explains the previously observed distribution of ice shelf
densification, which in parts had reached levels that preceded the collapse of Larsen B Ice Shelf,
suggesting a potential role for föhn winds in promoting unstable conditions on ice shelves.